CORTICOTHALAMIC REGULATION OF THALAMIC NUCLEI BY THE SOMATOSENSORY CORTEX DURING “HIGHER-ORDER”SENSORY INFORMATION PROCESSING

To navigate through environment rodents relay on the somatosensory system. The obtained tactile information is transmitted from the whiskers, via brainstem and thalamus (ventral posterior medial thalamus (VPM) and the posterior medial thalamus (POm)) to the somatosensory cortex (S1). Reciprocal connections between S1 and thalamic relay neurons fine-tune ongoing somatosensory signal processing. Corticothalamic projections from S1 layer 6 send inputs to these structures. S1L6B projections express the dopamine D1 receptor (Drd1) and project to POm. Another cell population in S1L6, that expresses the neurotensin receptor 1 (Ntsr1) projects to VPM, POm and nRT. Previously we found indications that these discrete corticothalamic pathways from S1L6 regulate somatosensory thalamus in a context-dependent manner, that supports fine-tuning of somatosensory perception. But the building of a meaningful picture of the environment not only requires dynamically timing of theses corticothalamic loops, but also the involvement of higher-order structures. To explore this aspect, we used Cre-driver mouse lines for Drd1 or Ntsr1 and transfected Drd1 and Ntrsr1-expressing neurons in S1L6 with archaerhodopsin. We photoinactivated the S1L6-corticothalamic pathways in combination with unexpected whisker deflections during states of whisking and use a Fluoreszence-in situ-Hybridization approach to detect neurons engaged in these two distinct S1L6-corticothalamic feedback loops during sensory processing. Our preliminary data reveal the involvement of the zona incerta and different areas of the prefrontal cortex, as well as the cingulate cortex and the medial orbitofrontal cortex.
Acknowledgment: Funded by a German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) grant to D.M.V (SPP 2411 - project number: 520284247).